Modification of titanium dioxide nanoparticles with copper oxide for photocatalytic degradation of 2,4-dichlorophenoxyacetic acid

Abstract

2,4-Dichlorophenoxyacetic acid (2,4-D) is a common herbicide that has been used in control of broadleaf weeds, wheat, corn, pastureland, lawn, recreational lakes, turf; and roadsides. Due to it excessive usage, these herbicides that contained 2,4-D can cause contamination over agricultural land and water bodies. Photocatalytic removal environmental pollutants such as herbicides has been a topic of great interest over the years 1. One of the most widely used materials for photocatalytic degradation of environmental pollutants is TiO,. A number of strategies have been developed in order to improve the catalytic activity of TiO, photocatalyst. In particular, it has been shown that transition metal oxides, such as copper oxide, are potential to enhance the photocatalytic activity of TiOl". In the present work:, a simple impregnation method was used to modify the commercial P25 TiD, nanoparticles with the copper oxide. The prepared samples were characterized by XRD, reflectance UVvisible and fluorescence spectroscopies. It was observed that the incorporation of copper oxide did not significantly affect the crystal structure of TiD,. On the other hand, the presence of copper oxide was confirmed by reflectance UV-visible and fluorescence spectroscopies. Figure I shows the photocatalytic removal of 2,4-D on bare TiD, and modified TiO,nanoparticles. It can be clearly shown that after I hour reaction, the photocatalytic activity of TiD, increased from 48 to 54% with the increase of copper oxide loading up to 0.5 mol%. Unfortunately, the higher loading amount of copper oxide resulted in the lower photocatalytic activity. When the loading amount was 5 mol%, the activity decreased to 26%. This result clearly suggested that the small amount of copper oxide, which was 0.5 mol%, was the optimum amount in this study to give the highest activity for the copper oxide supported on TiD, series. The higher photocatalytic activity would be originated from the lower electron-hole recombination.